Methods and apparatus for preserving pallet units of fresh perishables in modified atmosphere-containing bags

ABSTRACT

Methods and apparatus for enclosing a palletized container of fresh containers of perishables inside a modified atmosphere-containing plastic bag stretched over the containers and over upwardly-extending margins of a plastic sheet placed between the pallet and the containers to seal the containers of perishables inside the bag and to facilitate forming a modified atmosphere inside the bag.

BACKGROUND OF THE INVENTION

The fresh perishables trade uses modified atmosphere technologies onbagged and sealed pallet unit quantities of perishables to preservefreshness and reduce market losses during distribution. Current systemsrequire that a pallet bag be placed over a unitized pallet ofperishables, which are placed in containers. The pallet bag is thensealed to a plastic sheet positioned on top of the pallet under theunitized containers of perishables. Once the pallet bag is sealed,desired quantities of one or more gasses are injected into the palletbag, creating a modified atmosphere, which benefits the enclosedperishables. U.S. Pat. Nos. Bolejack, et al. 5,014,495; 5,046,302;5,111,639; and 5,314,286; Forgnone, et al. 6,532,717; and MacLeod, etal. 4,821,489 describe such methods and apparatus.

There is a need to improve the automation and consistency of the currentsystems. Current systems require up to three persons to operateeffectively. These systems produce completed pallets at a rate of oneper minute. The new methods and apparatus, with preferred embodiments,provide automated systems capable of reliably producing a finishedpallet every 30 seconds, with fewer persons needed to operate thesystem.

SUMMARY OF THE INVENTION

A pallet bearing a plurality of containers of fresh perishables isplaced on a conveyor. The perishables load is conveyed to a stationwhere the unitized load is squeezed and lifted from the pallet, or issqueezed and the pallet lowered from the load, and a plastic sheet isautomatically inserted on the pallet in the gap created above the palletand below the suspended load. The margins of this bottom sheet extendbeyond the edges of the pallet on all sides. See Bolejack, et al. U.S.Pat. Nos. 5,014,495; 5,111,639, and 5,314,286; and Forgnone, et al.,U.S. patent application Ser. No. 10/785,868, filed in the United StatesPatent and Trademark Office Feb. 24, 2004, entitled “Apparatus AndMethods For Enclosing Product Units,” for disclosures of such apparatusand methods. After the sheet is in place, and the containers ofperishables are placed atop the pallet and sheet, the resulting palletunit is conveyed to a bagging station. There, a plastic bag isautomatically applied from above the palletized unit. The bag isstretched over, and then down the exterior surfaces of the stacked unit.Once the stretched film is released, the film, which forms a bag, iseffectively pulled tightly against the exterior surfaces. Tension of thestretched bag against the pallet unit surfaces is also sufficient tobrace/stabilize the palletized unit.

The new system may automatically position the overhanging margins of thebottom sheet upwards, against the sides of the perishables containersatop the pallet. The system then holds the sheet margins in a verticalposition long enough for the descending bag to overlap and capture thesheet margins, and to hold the margins in the vertical, upward positionagainst the perishables containers, inside the margins of the stretchedbag. The bag opening is preferably positioned above the plane of thepallet surface, leaving a portion (e.g., two inches) of the verticallypositioned bottom sheet exposed. The bag overlaps the remaining portionsof the bottom sheet. Because the bag has been stretched, the elasticityof the bag pulls tight against, and holds the sheet margins in place.Once held by the stretched bag, the system holding the sheet marginsupwards is withdrawn or cycled off. Alternatively, the sheet margins mayoverlie the margins at the opening of the bag.

Some perishables items require only one gas to create an appropriatemodified atmosphere. For strawberries, this gas may be carbon dioxide.Typically, after bagging and sealing, any gases may be injected.Alternative, gases may be delivered over the perishables inside the bagas the bag is stretched over the perishables containers prior tosealing. A shrink hood stretching mechanism stretches the bag out anddown adjacent to each corner of the unitized perishables. Gas deliverynozzles for creating a modified atmosphere environment inside the bagmay be positioned under each corner of the bag stretching device. Whenactivated, these nozzles deliver appropriate quantities of one or moregasses inside the bag to form a desired modified atmosphere as the bagis pulled and stretched over the unitized loads.

After leaving the bagging station, an in line tape or stretch wrap sealmay be applied to the bag margins which overlap thevertically-positioned bottom sheet margins. The bag margins preferablylie substantially flat against the margins of the sheet and thecontainer surfaces, providing a substantially smooth surface for tape orstretch film to be applied. Once properly applied, a seal is formed andsubstantially no gases may escape from the interior of the bag. Theseflat surfaces may also facilitate heat sealing of the bag to the sheetmargins. See, e.g., U.S. Pat. Nos. Bolejack, et al. 5,014,495;5,046,302; 5,111,639; and 5,314,286; Forgnone, et al. 6,532,717; andMacLeod, et al. 4,821,489 describing such methods and apparatus.

The permeability of the bag is preferably tailored to a specificperishable item. To form and maintain a desired modified atmosphereinside the sealed bag, the weight of the perishables must also bedetermined. By weighing each pallet, the respiration load of theperishable inside the enclosed bag can be determined. Based on thisdata, a system for punching or cutting calibrated holes in the palletbag forms one or more appropriate openings in the bag, and/or anappropriate hole such that a breathing membrane or label may be placedover such a hole. The size of hole and type of label varies with thetype and weight of the perishables item, and with the gas permeabilityof the bag. The breathing labels and/or calibrated holes help tomaintain a desired modified atmosphere inside a bag, by balancing thedesired components, e.g., carbon dioxide and oxygen, with the filmpermeability and perishable respiration load.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will becomeapparent in light of the following detailed description, taken togetherwith the accompanying drawings, in which:

FIG. 1 shows a schematic plan view of a preferred embodiment of a layoutof the bagging system of this invention;

FIG. 2 shows a perspective view of a system for applying a bag to apallet of containers of perishables, and for forming a modified gasatmosphere inside the bag;

FIG. 3 shows a first embodiment of a system for positioning and holdingthe margins of a plastic pallet sheet vertically against the sides ofpalletized containers of perishables;

FIG. 4 shows a side elevation view of the plastic pallet sheet marginspositioning/holding system device shown in FIG. 3;

FIG. 5 shows the operation of the device shown in FIGS. 3 & 4;

FIG. 6 shows a second embodiment of a device for holding the margins ofa plastic pallet sheet vertically against the side of palletizedcontainers of perishables;

FIG. 7 shows an embodiment of a system for delivering one or moremodified atmosphere gases under a bag as the bag descends over apalletized perishables load;

FIG. 8 shows an embodiment of a station for taping the opening of aplastic bag to the margins of a plastic sheet that are positionedvertically against containers of perishables atop a pallet and plasticsheet;

FIG. 9 shows a side elevation view of a system for forming one or moreholes in bags placed over a palletized load of containers of perishablesfor purposes of forming and maintaining a desired modified atmosphereinside such bags;

FIG. 10 shows the hole forming system of FIG. 9 in operation; and

FIG. 11 shows a hole formed by the device shown in FIGS. 9 and 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic, plan view of palletized container of perishablesbagging apparatus 10. In apparatus 10, conveyor 11 moves a plurality ofpallets, each loaded with a plurality of containers of perishables,e.g., strawberry containers, stacked on the upper surface of the pallet.As an example, a pallet may carry 16 tiers, with six trays in each tier,and have an overall height of about 90 inches. Each tray may contain aplurality of strawberry baskets. The pallet itself may have acircumference in the range of 150 to 200 inches, and be rectangular orsquare in shape. Where the perishable is strawberries, the strawberriesare preferably cooled to a temperature of about 33 degrees F., or about4 degrees F. above the freezing point of the strawberries. Theperishables are preferably cooled to, and maintained at an optimumstorage temperature, before the bagging operation begins.

A plurality of pallets, each loaded with perishables, may be brought toin-feed 11, e.g., by forklift. In-feed 11 conveys the pallets, one at atime, to squeeze station 12. At squeeze station 12, hydraulicallyactuated, one or two pairs of opposed vertical walls are activated toengage and squeeze the pallet load of containers of perishables abovethe pallet with sufficient force to permit the floor plate beneath thepallet to be lowered from the load supporting position, or to raise thepallet load from the pallet. See, e.g., U.S. Pat. Nos. Bolejack, et al.5,014,495; 5,046,302; 5,111,639; and 5,314,286; Forgnone, et al.6,532,717; and MacLeod, et al. 4,821,489 describing such methods andapparatus. After the pallet and load have been separated from oneanother, a plastic sheet is automatically placed on the pallet in thegap formed between the unitized load and the pallet. The inserted sheetthen rests on the pallet's upper surface. This sheet is generally flat,and the margins of the sheet extend beyond the edges of the pallet.After placement of the sheet on the pallet, the pallet may then beraised, or the pallet load may be lowered, to replace the perishablescontainers onto the plastic sheet atop the pallet. The pallet, with itsplastic sheet and perishables atop the plastic sheet, is then conveyedon path 13 into bagging station 14.

At bagging station 14, a plastic bag of appropriate size, shape, typeand gas permeability is automatically applied. The bag descends from abag supply above the pallet of perishables, and is stretched to fit overthe perishables and unitized containers of perishables. Simultaneously,the system automatically positions the overhanging margins of the decksheet upwards to a vertical position against the sides of theperishables containers. The system holds these margins in this positionfor a time sufficient for the descending bag to overlap and capturethese margins in the vertical upward position against the sides of thecontainers, and now inside the stretched pallet bag. The margins at theopening of the bag are positioned above the pallet, leaving a portion ofthe vertically-extended sheet margins exposed. Because the bag has beenstretched, and released against the load, the elasticity of the bagpulls tight against, and holds the vertically positioned margins of thesheet in place. Thereafter, the system holding the sheet marginsvertically upwards is withdrawn or cycled off Bagging apparatus of thistype are, for example, the automatic Lachenmeier, Beumer, and Moellerstretch hood machine.

In preferred embodiments, as a bag descends over the perishables on thepallet, one or more gasses appropriate for creating a desired modifiedatmosphere inside the bag, and over the perishables, may be injectedunder the bag to blanket or cover the perishables as the bag isstretched over the perishables load. For this purpose, nozzles may bepositioned under one or more corners of the bag so the bag descends overthe perishables so that the gas is delivered at up to four locations, toform a desired modified atmosphere inside the bag.

The bagged palletized perishables leave bagging station 14 and passes onpath 15 to sealing station 16. There, a taping mechanism applies tape orother suitable material where the bag overlaps the decking sheet,preferably around the entire circumference of the bagged palletizedcontainers of perishables creating a substantially air-tight seal. Thesealed palletized bagged perishables unit then passes on path 15 toweighing scale 18, for weighing. Using the weight of this unit, and thenature and temperature of the perishables, the respiration load for theperishable can be determined. From scale 18, the unit passes on path 17to station 19 where, based in part on the measured weight, orrespiration load, calibrated holes are formed in the bag as appropriateto maintain the desired modified atmosphere within the bag. Labels,membranes or other such devices may also, or alternatively, be appliedto the bag to modify the permeability of the bag, and maintain a desiredmodified atmosphere within the bag for the respiration load asdetermined.

FIG. 2 shows pallet 22 bearing a load of perishables 20 with plasticsheet 21 between the pallet's upper surface and the bottom surface ofthe perishables. Sheet 21 extends over the margins of pallet 22 on allfour sides.

FIGS. 3, 4 and 5 show scissors mechanism 23 which supports blades 24 and27. As scissors mechanism 23 moves upward, blades 24 and 27 engage andmove the margins of sheet 21 into the vertical position alongside theedges of the palletized load. These blades hold the margins in thisvertical position until the bag has descended over the perishables, andover the margins of sheet 21. FIG. 4 shows blade 27 holding the sheetmargins vertically against the side of the palletized load 20.

FIG. 6 shows the margins of plastic sheet 21 alternately held invertical position by means of air from blowers 30 through 36. This airis delivered from compressor 37 through manifold 38.

FIG. 7 shows gas delivery system 40, which includes gas tanks 41 and 42,valve 43, manifold 44, hoses 45, 46, and 47, and nozzles 48, 49, and 50.In preferred embodiments, this gas delivery system delivers one or moregases inside the pallet bag as it descends over the palletized load toform a desired modified atmosphere inside the bag.

FIG. 8 shows unit 51, a bagged modified atmosphere-blanketed pallet ofcontainers of perishables at taping station 16 where taping mechanism 52applies tape to the periphery 53, where the bag overlapsvertically-extending deck sheet margins to seal them to one another.Alternatively, in FIG. 8, track 54A drives the tape mechanism around thepallet. The unitized load is stationery while the taping mechanism movesaround the stationery load.

FIG. 9 shows system 60 for forming calibrated holes in the bag as anadjunct to maintaining the desired modified atmosphere inside the bag.In FIG. 9, this system is located at station 19. Hole-forming system 60includes air compressor 61, controls 62 and manifold 63, one-way valve64, and hole-forming cutter 66 with serrated blades formed on surface67. Cutter 66 is housed within safety collar 68 and is actuated bydepressing switch 69 on handle 70.

FIG. 10 shows an elevation view of hole-forming system 60 appliedagainst bag surface 70 of unit 71. With collar 68 resting against bagsurface 70, cutter 66 moves (right to left) to cut into and form holesof desired shape and pattern on bag surface 70. Cutter 66 is withdrawnand a special membrane may then be applied to cover the hole.

After the hole-punch and the calibrated membrane application processes,the completed, bagged, unitized pallet containing a desired modifiedatmosphere moves along on exit conveyor 19. A forklift can then removethe unitized pallet load for storage/distribution.

1. (canceled)
 2. Apparatus comprising: a squeezer for temporarilysupporting containers of perishables above a pallet creating a gap suchthat a plastic sheet may be placed atop said pallet with margins of saidsheet extending beyond the perimeter of said pallet; a bag dispenserthat stretches a plastic bag over said perishables and said containersand over the upwardly extending margins of the plastic sheet; thenreleases the stretching force so that said bag fits tightly over saidperishables and said containers; and a sealer for sealing said palletand said perishables inside of said plastic bag.
 3. (canceled) 4.(canceled)
 5. (canceled)
 6. (canceled)
 7. (canceled)
 8. The apparatus ofclaim 2, wherein said sealer comprises a heat sealer, a tape sealer, awrapping system, or a gluing system.
 9. The apparatus of claim 2,further comprising a gaseous pressure system or a mechanical system forpositioning and holding the margins of said plastic sheet verticallyupwardly from said pallet against the sides of said containers. 10.(canceled) 11-22. (canceled)
 23. The apparatus of claim 2 furthercomprising a gas delivery system for delivering a gaseous modifiedatmosphere inside said bag.
 24. The apparatus of claim 23 wherein saidgas delivery system includes a plurality of injectors for delivering oneor more gases inside said bag.
 25. The apparatus of claim 24 whereinsaid gas delivery system includes one or more injectors linked to saidbagging system.
 26. The apparatus of claim 2 or claim 23 or claim 24further comprising a hole-forming device for forming one or more holesin one or more sides of said bag to form and to maintain a desired,modified atmosphere inside said bag.
 27. The apparatus of claim 2 orclaim 23 or claim 24 further comprising a system for forming a desiredmodified atmosphere inside said bag based on the nature of theperishables, the weight of the perishables, and on the respiration loadof the perishables inside said bag.
 28. Apparatus comprising a systemfor sealing containers of perishables on a pallet that has a plasticsheet atop said pallet and beneath said containers, with margins of saidsheet extending beyond the perimeter of said pallet; inside a plasticbag stretched tightly over said perishables, over said containers andover the upwardly extending margins of the plastic sheet that includes asealer for sealing said pallet and said perishables inside of saidplastic bag, and a system for forming a desired modified atmosphereinside said bag based on the nature of the perishables, the weight ofthe perishables, the permeability of the bag to oxygen and carbondioxide, and on the respiration load of the perishables inside said bag.29. The apparatus of claim 28 further comprising a hole-forming devicefor forming one or more holes in one or more sides of said bag to formand to maintain a desired, modified atmosphere inside said bag.
 30. Theapparatus of claim 9 wherein said system further comprises a system thatsecures said margins in a vertically upward position.